The problem with the milk and gastro (that is if you are going both ends) is that as soon as it hits the stomach it curdles which is why it comes back up. Rule of thumb my doc told me was if vomiting steer away from dairy, if it's just the bum then do everything bad as far as diet to bind it up... so meat, fatty stuff, white bread... stay away from the fruits etc... fibre.

Lemonade you really need to be careful with as it can cause dehydration like muminalice said. I found a good website was kids health... I think it's a dot org one. Hope your family gets better really fast. I really hate that bug!!